1. Field of the Invention
The present invention relates to dynamo-electric machines for apparatuses such as alternators driven by, for example, internal combustion engines. In particular, the present invention relates to an armature for an automotive alternator to be mounted on an automotive vehicle, such as an automobile or a truck.
The entire content of the basic Japanese Patent Application from which the priority under the Convention is claimed in this application is hereby incorporated by reference into this application.
2. Description of the Related Art
FIG. 27 is a perspective view of a stator for a known automotive alternator.
In FIG. 27, a known stator 1 includes a stator core 2 provided with a plurality of slots 2a extending in the axial direction and disposed alongside each other in the circumferential direction at a predetermined pitch, a stator winding 3 mounted on the stator core 2, and substantially U-shaped insulators 4 disposed in the slots 2a for electrically insulating between the stator core 2 and the stator winding 3. Thirty-six slots 2a are formed in the stator core 2 for receiving the stator winding 3 configured with a three-phase alternating winding.
With reference to FIGS. 28 to 34, a method for manufacturing the known stator 1 is described below.
A belt-shaped member having projections and recesses is made of a belt-like magnetic SPCC thin plate. A given number of the belt-shaped members are laminated and are welded to each other by a laser at the peripheries thereof, thereby forming a rectangular parallelepiped laminated-core 5 shown in FIG. 28. Thirty-six slots 5a are formed at one face of the laminated core 5.
A winding assembly 7A is formed in a plane shape with one strand of wire 6, made of a copper wire having a circular section and coated with an insulating film, wound in a predetermined number of waves at a three-slot pitch. The winding-starting end and the winding-finishing end of the strand of wire 6 forming the winding assembly 7A serve as a lead wire 6a and a neutral-point lead wire 6b, respectively. Winding assemblies 7B and 7C are formed with other two strands of wire 6, respectively, wound in the same manner.
In FIG. 29, a substantially U-shaped insulator 4 is inserted in each slot 5a of the laminated core 5 from the open side of the slot 5a, whereby the insulator 4 is received completely in the slot 5a. The three winding assemblies 7A, 7B, and 7C overlap each other by being offset by a one-slot pitch from each other, as shown in FIG. 30. In FIG. 31, the overlapping winding assemblies 7A, 7B, and 7C are inserted in every third slots 5a, respectively, from the open sides of the slots 5a. As shown in FIGS. 32 and 33, the winding assemblies 7A, 7B, and 7C are thus mounted on the laminated core 5.
In FIG. 34, the laminated core 5 mounted with the winding assemblies 7A, 7B, and 7C is rolled up and is formed in a cylinder by a forming device (not shown), and butt-welded by a laser at the longitudinal ends thereof, whereby the stator 1 shown in FIG. 27 is obtained.
The neutral-point lead wires 6b of the strand of wires 6 forming the winding assemblies 7A, 7B, and 7C are connected to each other, thereby forming a three-phase alternating winding constituting the stator winding 3 included in the known stator 1. The winding assemblies 7A, 7B, and 7C have a phase difference of 120 degrees from each other, which are windings for phase-a, phase-b, and phase-c, respectively, of the three-phase alternating winding. When the stator 1 is mounted in an automotive alternator, the lead wires 6a of the strands of wire 6 forming the winding assemblies 7A, 7B, and 7C are connected to a rectifier.
In a method for manufacturing the known stator, the substantially U-shaped insulators 4 are inserted in the slots 5a of the rectangular parallelepiped laminated core 5, then the winding assemblies 7A, 7B, and 7C are inserted in the slots 5a from the open sides thereof. Since the gap between the stator 1 and a rotor (not shown) of an automotive alternator is very small, even a small protrusion of the insulator 4 from the slot 5a may interfere with the rotator. Therefore, the insulators 4 are formed so as not to protrude from the slots in the radial directions.
Therefore, there is a problem that the mounting operation of the winding assemblies is not easy to perform because the ends of the insulators 4 are disposed substantially on the same level as that of the ends of teeth 5b, whereby the ends of the insulators 4 do not function as guides when the winding assemblies 7A, 7B, and 7C are inserted in the slots 5a. 
Two sides of each U-shaped insulator 4, opposing to each other, are formed in parallel to each other, and the open sides of the slots 5a are not closed when the winding assemblies 7A, 7B, and 7C have been received in the slots 5a. Therefore, during the operation of rolling the laminated core 5, the strand of wires 6 are likely to fall away from the slots 5a, whereby the operation cannot be performed efficiently.
The ends of the insulators 4 are drawn toward the bottoms of the slots 5a during the insertion of the winding assemblies 7A, 7B, and 7C due to the friction between the winding assemblies 7A, 7B, and 7C and the insulators 4, whereby flanges 5c of the teeth 5b are exposed at ends thereof in the peripheral direction of the laminated core 5. Therefore, there is a problem in that the strands of wire 6 of the winding assemblies 7A, 7B, and 7C are scratched by the peripheral ends of the flanges 5c, thereby causing damages to the insulating films of the strand of wires 6, whereby the insulation is deteriorated. Moreover, the insulators 4 between the inner walls of the slots 5a and the strands of wire 6 are removed from some portions in the slots 5a after inserting the winding assemblies 7A, 7B and 7C in the core, whereby the insulation is deteriorated.
Accordingly, it is an object of the present invention to provide a method for manufacturing an armature for a dynamo-electric machine and an armature manufactured by the method, in which a substantially U-shaped insulator having top sides thereof bent so as to be apart from each other is mounted in each slot in a manner such that the top sides of the insulator protrude from the slot, and a winding assembly is inserted in the slots from open sides thereof. The winding assembly can be easily inserted due to the top sides of the insulator serving as guides. Due to the top sides of the insulator, which are bent so as to be apart from each other, strands of wire forming the winding assembly inserted in the slots are prevented from falling away from the slots by the top sides deformed so as to enclose an opening of each slot, and the insulator is prevented from being removed the top edges thereof toward the bottom of the slot, thereby improving the insulation.
To these ends, according to an aspect of the present invention, a method is provided for manufacturing an armature for a dynamo-electric machine, the armature comprising an armature core provided with a plurality of slots extending in an axial direction and disposed alongside each other in a circumferential direction, an armature winding inserted in the slots so as to be mounted on the armature core, and an insulator mounted in each of the slots for insulating between the armature core and the armature winding. The method comprises the steps of forming a substantially U-shaped insulator having side portions connected with a bottom portion, the side portions being bent at a first bent part of each side portion so as to be apart from each other to form outwardly bent portions on the top sides of the side portions; forming a winding assembly composed of strands of wire formed in a predetermined wound state; mounting the insulator in each of the plurality of slots in a manner such that the outwardly bent portions of the insulator protrude from an open side of the slot; and inserting the winding assembly in the insulator from the open side of each slot by being guided by the outwardly bent portions of the insulator, and pushing the winding assembly together with the insulators into the slots.
In the method for manufacturing an armature for a dynamo-electric machine, the step of forming the substantially U-shaped insulator may include the step of bending the outwardly bent portions at a second bent part so as to be close to each other, whereby each of the outwardly bent portions is formed in an L-shape.
The first and second bent parts of one of the side portions of the insulator may be positioned shifted toward the bottom portion of the insulator with respect to the first and second bent parts of the other side portion of the insulator.
At least one part of the bottom portion of the insulator may be formed in one of concave and convex shapes.
The method may further comprising the steps of preparing a rectangular parallelepiped laminated-core provided with the plurality of slots, and rolling the rectangular parallelepiped laminated-core provided with the insulator mounted in each of the plurality of slots and the winding assembly inserted in the insulators mounted in the plurality of slots and butt-welding the laminated core at ends thereof so as to form a cylinder.
The winding assembly may be formed so that the strands of wire are disposed alongside each other in the slot-depth direction in each slot.
The winding assembly may comprise a pair of first and second winding groups, the first winding group comprising a number of first winding sub-portions each formed with the strand of wire made of a continuous conductor, the strand of wire being formed in a first wave shape by connecting straight portions which being disposed at a pitch of a predetermined number of slots and being alternately offset from each other by a predetermined distance in a direction perpendicular to the direction of the disposition thereof with turn portions, the first winding sub-portions being disposed at a pitch of one slot from each other and being equal in number to the predetermined number of slots, and the second winding group comprising a number of second winding sub-portions each formed with the strand of wire made of a continuous conductor, the strand of wire being formed in a second wave shape opposite to the first wave shape by connecting straight portions which being disposed at a pitch of the predetermined number of slots and being alternately offset from each other by the predetermined distance in a direction perpendicular to the direction of the disposition thereof with turn portions, the second winding sub-portions being disposed at a pitch of one slot from each other and being equal in number to the predetermined number of slots.
A plurality of the winding assemblies overlapping each other may be inserted in the plurality of slots.
The steps of mounting the insulator in each of the plurality of slots and inserting the winding assembly in the insulators mounted in the plurality of slots may be alternately and repeatedly performed.
According to another aspect of the present invention, an armature for a dynamo-electric machine comprises an armature core provided with a plurality of slots extending in an axial direction and disposed alongside each other in a circumferential direction; an armature winding inserted in the slots so as to be mounted on the armature core; and an insulator mounted in each of the slots for insulating between the armature core and the armature winding. The insulator is disposed between an inner face of each slot and the armature winding. First creases are formed on side portions of each insulator so as to extend in a longitudinal direction of the slot at a slot-opening side of the side portions, the first creases being formed by first bent parts for bending the slot-opening side of the side portions so as to be apart from each other.
Second creases may be formed on the side portions of each insulator so as to extend in a longitudinal direction of the slot at a slot-opening side of the first creases, the second creases being formed by second bent parts for bending the slot-opening side of the side portions so as to be close to each other.
The first crease and the second crease of a first side portion of each insulator may be formed shifted toward the bottom of the slot with respect to the first crease and the second crease, respectively, of a second side portion of each insulator, whereby the top sides of the first and second side portions of each insulator, one overlapping the other, enclose an opening of each slot in a manner such that the top side of the second side portion is positioned over the top side of the first side portion.
The side portions of each insulator may expand in a circumferential direction at the bottom sides of the side portions of the insulator, thereby coming into close contact with inner faces of the slot toward the bottom thereof.
The armature winding may be constituted by at least one winding assembly into which a pair of first and second winding groups is assembled before insertion in the slots, the first winding group comprising a number of first winding sub-portions each having one turn constructed by winding a stand of wire made of a continuous conductor so as to alternately occupy an inner layer and an outer layer in a slot depth direction within the slots at intervals of a predetermined number of slots, the first winding sub-portions being disposed at a pitch of one slot from each other and being equal in number of the predetermined number of slots, and the second winding group comprising a number of second winding sub-portions each having one turn constructed by winding a stand of wire made of a continuous conductor so as to alternately occupy an inner layer and an outer layer in a slot depth direction within the slots at intervals of the predetermined number of slots and so as to be inversely wound and offset by an electrical angle of 180 degrees relative to the first winding sub-portions, the second winding sub-portions being disposed at a pitch of one slot from each other and being equal in number of the predetermined number of slots.
The armature winding may comprise a plurality of the winding assemblies, and one insulator may be received in each slot for insulating the plurality of the winding assemblies from an inner face of each slot.
The armature winding may comprise a plurality of the winding assemblies, and a plurality of insulators may be received in each slot for individually insulating the plurality of the winding assemblies from an inner face of each slot.